Supported molybdenum oxides as effective catalysts for the catalytic fast pyrolysis of lignocellulosic biomass

The catalytic fast pyrolysis (CFP) of pine was investigated over 10 wt% MoO[subscript 3]/TiO[subscript 2] and MoO[subscript 3]/ZrO[subscript 2] at 500 °C and H[subscript 2] pressures ≤0.75 bar. The product distributions were monitored in real time using a molecular beam mass spectrometer (MBMS). Both supported MoO[subscript 3] catalysts show different levels of deoxygenation based on the cumulative biomass to MoO[subscript 3] mass ratio exposed to the catalytic bed. For biomass to MoO[subscript 3] mass ratios <1.5, predominantly olefinic and aromatic hydrocarbons are produced with no detectable oxygen-containing species. For ratios ≥1.5, partially deoxygenated species comprised of furans and phenols are observed, with a concomitant decrease of olefinic and aromatic hydrocarbons. For ratios ≥5, primary pyrolysis vapours break through the bed, indicating the onset of catalyst deactivation. Product quantification with a tandem micropyrolyzer–GCMS setup shows that fresh supported MoO[subscript 3] catalysts convert ca. 27 mol% of the original carbon into hydrocarbons comprised predominantly of aromatics (7 C%), olefins (18 C%) and paraffins (2 C%), comparable to the total hydrocarbon yield obtained with HZSM-5 operated under similar reaction conditions. Post-reaction XPS analysis on supported MoO[subscript 3]/ZrO[subscript 2] and MoO[subscript 3]/TiO[subscript 2] catalysts reveal that ca. 50% of Mo surface species exist in their partially reduced forms (i.e., Mo5[superscript +] and Mo3[superscript +]), and that catalyst deactivation is likely associated to coking.BP (Firm) (MIT Energy Initiative. Advanced Conversion Research Program)National Science Foundation (U.S.) (Award 1454299

Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

BACKGROUND Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. METHODS The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model-a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates-with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality-which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. FINDINGS The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2-100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1-290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1-211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4-48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3-37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7-9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. INTERPRETATION Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. FUNDING Bill & Melinda Gates Foundation

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Catalytic upgrading of biomass through the hydrodeoxygenation (HDO) of bio-oil derived model compounds

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2017.Cataloged from PDF version of thesis.Includes bibliographical references.Lignocellulosic biomass is an attractive renewable source for fuels and chemicals. Of the many conversion alternatives, catalytic fast pyrolysis has emerged as an attractive technology to convert biomass into fuel additives and value-added chemicals. Current pyrolysis oils or bio-oils are incompatible with refinery streams due to their high acid, water, and water content. The key roadblock in its commercial exploitation is development of catalytic platforms for selective deoxygenation along with minimum hydrogen consumption and carbon loss. Current catalytic solutions including zeolites, and conventional hydrotreating catalysts employ high hydrogen pressures, leading to aromatic ring hydrogenation, and hydrogen consumption. This thesis focusses on developing fundamental catalytic understanding on cheaper and earth-abundant reducible transition metal oxide catalysts for selective hydrodeoxygenation (HDO) of bio-oil derived model compounds using reactivity, computation and characterization studies. The first section focuses on developing structure-reactivity relationships on bulk and supported MoO₃ catalysts for the HDO of lignin-derived model compounds. Characterization reveals that MoO₃ undergoes reduction to catalytically inactive MoO₂ at a temperature of 673 K, and stabilization of partially reduced MoO₃ surface through its partial carburization to oxycarbide phase (MoOxCyHz) at temperatures < 623 K. Thereafter, TiO₂ and ZrO₂ supports prevent the reduction of dispersed oligomeric MoOx species to catalytically inactive species, enhancing their stability. In addition, the overall catalyst reactivity inversely correlates to the maximum hydrogen consumption temperature during hydrogen temperature programmed reduction (H₂-TPR). Furthermore, a near-monolayer oligomeric MoOx dispersion on ZrO₂ support was found to be optimum for HDO reactivity. The second section focuses on developing mechanistic insights into the HDO on bulk and supported MoO₃ with the aid of density functional theory (DFT) computations and kinetic studies. DFT computations were carried out on the elementary steps for HDO of acetone-a model compound on pristine [alpha]-MoO₃ (010) surface to reveal dissociative H₂ adsorption on the (010) surface to be the rate-limiting step. Kinetic studies on MoO₃ supported on ZrO₂ reveal the differences in reaction mechanism and the nature of active sites for HDO on MoO₃/ZrO₂ as compared to bulk MoO₃. The third section focuses on generalizing the low-temperature (< 523 K) selective HDO on other reducible base metal oxides, specifically cobalt oxide and demonstrates oxides to have significantly higher reactivity than base metals for HDO. Finally, lanthanum strontium cobaltite (La₀.₈Sr₀.₂CoO₃), a perovskite oxide, was demonstrated as a novel HDO catalyst at < 523 K. Overall, this thesis provides a toolkit for developing structure-reactivity relationships on reducible metal oxides for their use as HDO catalysts.by Manish Shetty.Ph. D

Challenges and opportunities for exploiting the role of zeolite confinements for the selective hydrogenation of acetylene

Zeolites, with their ordered crystalline porous structure, provide a unique opportunity to confine metal catalysts, whether single atoms (e.g., transition metal ions (TMIs)) or metal clusters when used as a catalyst support. The confined environment has been shown to provide rate and selectivity enhancement across a variety of reactions via both steric and electronic effects such as size exclusion and transition state stabilization. In this review, we provide a survey of various zeolite confined catalysts used for the semi-hydrogenation of acetylene highlighting their performance, defined by ethylene selectivity at full acetylene conversion, in relationship to the synthesis technique employed. Synthesis methods that ensure confinement with catalyst transition metal location in the extra-framework positions are observed to have the report the highest selectivity to ethylene. However, the underlying molecular factors responsible for selective catalysis within confinement remains elusive due to the difficulty of deconvoluting individual effects. Through the careful use of a combination of characterization and spectroscopic methods, insights into the relationship between the properties of zeolite confined catalysts and their performance have been explored in other works for a variety of reactions. More specifically, operando spectroscopy studies have revealed the dynamic behavior of zeolite confined catalysts under various conditions implying that the structure and properties observed ex-situ do not always match those of the active catalyst under reaction conditions. Applying this type of analysis to acetylene semi-hydrogenation, a simple gas phase reaction, can help elucidate the structure-function relationship of zeolite confined catalysts allowing for more informed design choices and consequently their application to a wider variety of more complex reactions such as the liquid phase hydrogenation of alkynols where solvent effects must also be considered in addition to those of confinement

Elucidating the Role of Strain in Catalysis toward Modulating Surface-Adsorbate Interactions and Tuning Catalytic Activity

Strain has been shown to modulate adsorption and reactions on metal surfaces. While its effect on surface-adsorbate interactions has been rationalized, an understanding of the electronic factors that drive these interactions and their consequences on catalytic activity is lacking. In this work, we use ab initio density functional theory (DFT) and microkinetic modeling (MKM) to develop electronic descriptors that govern the effect of biaxial strain in the modulation of interactions between adsorbate and transition states with catalyst surface and report its significance in enhancing the activity of fcc Pd(111) in the synthesis of ammonia (NH3), an important renewable-energy and hydrogen (H2) vector. We established the p-band center (pcenter) of the adsorbates and transition states (TS) and the hybridized d-band center (dcenter) of the surface metal as key electronic descriptors for adsorbate and TS energy variations with strain. Specifically, the pcenter of the adsorbates is lowest for the sites with the strongest adsorption, and the upshift of the dcenter of the surface metal atoms is greatest for the adsorption site with the highest strain susceptibility (i.e., the change in adsorption energy per unit applied strain). Importantly, we showed significant deviations in scaling relations with strain compared to periodic scaling relationships, both for adsorption and reaction. Over a net 4% tensile strain (±2%), the dcenter of Pd(111) moved upward by 0.21 eV, enhancing N2 dissociation, the rate-determining step in NH3 synthesis by ~37×, and the pcenter in N bound to the catalyst surface moved downward in the adsorbed state and upward in the TS (i.e., electron density shifted toward the bonding and anti-bonding states, respectively). Thus, tensile strain played a dual role in enhancing N2 dissociation, strengthening the adsorption of atomic N and weakening the N-N bond in the TS. We then evaluated N2 dissociation at 3/4 ML H-coverage under industrial conditions (150 atm H¬2, 50 atm N2, and 723 K), revealing the effect of tensile strain on the rate enhancement to be nearly two orders of magnitude greater (~3273× vs. ~37×) at high surface coverages. Overall, this study highlights strain as a useful design tool to improve catalytic activity

Challenges and Opportunities for Exploiting the Role of Zeolite Confinements for the Selective Hydrogenation of Acetylene

Zeolites, with their ordered crystalline porous structure, provide a unique opportunity to confine metal catalysts, whether single atoms (e.g., transition metal ions (TMIs)) or metal clusters, when used as a catalyst support. The confined environment has been shown to provide rate and selectivity enhancement across a variety of reactions via both steric and electronic effects, such as size exclusion and transition state stabilization. In this review, we provide a survey of various zeolite confined catalysts used for the semihydrogenation of acetylene highlighting their performance, defined by ethylene selectivity at full acetylene conversion, in relationship to the synthesis technique employed. Synthesis methods that ensure confinement with the catalyst transition metal location in the extra-framework positions are reported to have the highest selectivity to ethylene. However, the underlying molecular factors responsible for selective catalysis within confinement remain elusive due to the difficulty in deconvoluting individual effects. Through the careful use of a combination of characterization and spectroscopic methods, insights into the relationship between the properties of zeolite confined catalysts and their performance have been explored in other works for a variety of reactions. More specifically, operando spectroscopy studies have revealed the dynamic behavior of zeolite confined catalysts under various conditions implying that the structure and properties observed ex situ do not always match those of the active catalyst under reaction conditions. Applying this type of analysis to acetylene semihydrogenation, a simple gas phase reaction, can help elucidate the structure–function relationship of zeolite confined catalysts allowing for more informed design choices and consequently their application to a wider variety of more complex reactions such as the liquid phase hydrogenation of alkynols where solvent effects must also be considered in addition to those of confinement

Sustainable Hybrid Route to Renewable Methacrylic Acid via Biomass-Derived Citramalate

Combined chemical technologies of microbial fermentation and thermal catalysis provides a hybrid process for sustainable manufacturing of biorenewable sugar-derived monomers for plastics. In this work, methacrylic acid (MAA), a target molecule for the polymer industry, was produced from biomass-derived glucose through the intermediate molecule, citramalic acid. The biosynthetic pathway engineered in E. coli produced citramalic acid intermediate with a high yield (91% of theoretical maximum) from glucose by overexpressing citramalate synthase, removing downstream degradation enzyme 3-isopropylmalate dehydratase, and optimizing the fermentation medium. Thermal heterogeneous catalysis converted the citramalate intermediate to methacrylic acid (MAA) via decarboxylation and dehydration. A selectivity of ~71% for the production of MAA and its intermediate α-hydroxybutyric acid was achieved at a temperature of 250 oC and an acidity of 1.0 mol acid/mol citramalate. An alumina catalyst was found to enhance selectivity to MAA in a single reactor pass from 45.6% in the absence of catalyst to 63.2%. This limited selectivity to MAA was attributed to equilibrium between MAA and α-hydroxybutyric acid, but overall process selectivity to MAA was shown to be higher upon separation and recycle of reaction intermediates. A process flow diagram was proposed of the hybrid route for the conversion of glucose to the final end product, methacrylic acid, for poly(methyl methacrylate) (PMMA)

Liquid supported denture-management of flabby ridges

The ideal properties of a denture are adequate rigidity on polished surface to bear masticatory forces and at the same time, flexibility and softness on the tissue surface for proper and even distribution of masticatory forces. The problem with conventional denture is rigidity of tissue surface; leads to uneven distribution of load. This drawback even worsens in the case of flabby, atrophic and unemployed ridges with excessive bone resorption.The liquid supported denture allows continued adaptation and eliminates the disadvantages of denture designs based on the application of temporary tissue conditioners or soft liners

Cooperative Co-0/Co-II sites stabilized by a perovskite matrix enable selective C-O and C-C bond hydrogenolysis of oxygenated arenes

Strontium-substituted lanthanum cobaltite (La0.8Sr0.2CoO3) matrix-stabilized Co-0/Co-II catalytic sites were prepared, which present tunable C-O and C-C hydrogenolysis activity for the vapor-phase upgrading of oxygenated arenes. Co-II sites associated with oxygen vacancies were favored at low temperatures and performed selective C-O hydrogenolysis, in which Sr-substitution facilitated oxygen vacancy formation, leading to approximately 10times higher reactivity compared to undoped LaCoO3. Co-0 sites were favored at high temperatures and performed extensive C-C bond hydrogenolysis, generating a wide range of alkanes. The lower reaction order with PH2 (1.1 +/- 0.1) for C-C hydrogenolysis than for C-O hydrogenolysis (2.0 +/- 0.1) led to a high selectivity towards C-C hydrogenolysis at low PH2 . The Co3O4 surfaces featured a narrower temperature window for obtaining the respective optimal Co-II and Co-0 pairs compared to analogous perovskite surfaces; whereas, the perovskite matrix stabilizes these pairs for selective C-O and C-C hydrogenolysis. This stabilization effect offers an additional handle to control reactivity in oxide catalysts121021712175CNPQ - Conselho Nacional de Desenvolvimento Científico e TecnológicoFAPESP – Fundação de Amparo à Pesquisa Do Estado De São PauloNSF - National Science Foundation14542992015/23900-2309373/2014-